Early developed catalysts for the alkylation and/or transalkylation of benzene are of Friedel-Crafts type, such as aluminium chloride, boron trifluoride, hydrofluoric acid. However, such catalysts bring about various problems such as separation of the catalyst from the product, corrosion of the process equipment and the three-waste pollution in industrial processes.
Such catalysts have been replaced or are being replaced by solid acid catalyst, especially zeolite catalyst, such as ZSM-5 zeolite employed in vapor phase process, ultrastable Y zeolite and zeolite beta employed in liquid phase process. U.S. Pat. No. 4,891,458 describes in detail a process of alkylation of benzene with C.sub.2 to C.sub.4 olefin or transalkylation of benzene with polyalkylbenzene using zeolite beta as catalyst. The catalyst used in the process are as follows. The pure zeolite beta may be used as a catalyst, but generally the catalyst comprises from 1 to 99% by weight, preferably from 10 to 90% by weight, more preferably from 60 to 80% by weight of zeolite beta in admixture with an inorganic oxide binder such as alumina, silica, silica/alumina, or naturally occurring clays. The zeolite beta used has a silicon to aluminium ratio of 5 to 100, preferably 5 to 50. It can be of Na type as-synthesized, or of a type of a metal ion selected from Groups IA, II A or III A, such as ions of lithium, potassium, calcium, magnesium, lanthanum, cerium, nickel, platinum, palladium, and the like, which is incorporated by ion exchange technique. However, for high catalytic activity, the zeolite beta should be predominantly of its H type, preferably at least 80 percent of the cation sites are occupied by hydrogen ions and/or rare earth ions. The zeolite beta catalyst can provide monoalkylated products in high yield and high product purity, and provide high yields of monoalkylated product for much longer periods of time than other zeolite catalysts.
Some patents report modification of zeolite-alumina catalyst with fluoride. For example, treatment of formed catalyst of ZSM type zeolite and alumina with fluoride, such as hydrofluoric acid, sodium fluoride, potassium fluoride, lithium fluoride, boron trifluoride, ammonium fluoride, increases remarkably the cracking activity (.alpha.value) of the catalyst (U.S. Pat. Nos. 4,427,786; 4,564,719; 4,538,014; 4,538,016; EP 134, 326 ) EP295, 020 discloses the treatment of deactivated zeolites such as zeolite USY, ZSM-5, beta with aqueous solution of NH.sub.4 F . HFimproves their cracking activity (.alpha.value) EP295, 019 discloses that zeolites such as USY, ZSM-5 and beta arc treated with aqueous solution of NH.sub.4 F . HF to remove non-frame work aluminium from their crystals and thus improved in their crystallinity.
However, there is no report up to now on the use of modified zeolite catalyst with halogen-containing compound in the alkylation or transalkylation of benzene.